Resizing a Root Volume for an Openstack Instance

This documents how to resize an OpenStack instance that has it's root partition backed by a volume. In this circumstance "nova resize" will not resize the diskspace as expected.

Assumptions:

• You have an existing OpenStack instance with a root volume.
• You do not have direct access to OpenStack block storage.
• You have already setup your workstation as an OpenStack management client.
• You are building all your VMs as volumes by default
• Following Change the size of your serve does not resize the volume for you.
• Your account has sufficient privileges in your tenant to perform this operation.

Shutdown the instance you wish to resize

Check the status of the source VM and stop it if it's not already:

$ nova list
+--------------------------------------+-----------+--------+------------+-
------------+---------------------------------------------+
| ID                                   | Name      | Status | Task State | 
Power State | Networks                                    |
+--------------------------------------+-----------+--------+------------+-
------------+---------------------------------------------+
| 4fef1b97-901e-4ab1-8e1f-191cb2f75969 | ResizeMe0 | ACTIVE | -          | 
Running     | Tutorial=192.168.0.107 |
+--------------------------------------+-----------+--------+------------+-
------------+---------------------------------------------+
$ nova stop ResizeMe0
$ nova list
+--------------------------------------+-----------+--------+------------+-
------------+---------------------------------------------+
| ID                                   | Name      | Status | Task State | 
Power State | Networks                                    |
+--------------------------------------+-----------+---------+-----------+-
------------+---------------------------------------------+
| 4fef1b97-901e-4ab1-8e1f-191cb2f75969 | ResizeMe0 | SHUTOFF | -          | 
Running     | Tutorial=192.168.0.107 |
+--------------------------------------+-----------+---------+------------+-
------------+---------------------------------------------+

Identify and extend the volume

Obtain the ID of the volume attached to the instance:

$ nova show ResizeMe0 | grep volumes
| os-extended-volumes:volumes_attached | [{"id": "616dbaa6-f5a5-4f06-9855-fdf222847f3e"}]         |

Set the volume's state to be "available" to so we can resize it:

$ cinder reset-state --state available 616dbaa6-f5a5-4f06-9855-fdf222847f3e
$ cinder show 616dbaa6-f5a5-4f06-9855-fdf222847f3e | grep " status "
| status | available |

Extend the volume to the desired size:

$ cinder extend 616dbaa6-f5a5-4f06-9855-fdf222847f3e 4

Set the status back to being in use:

$ cinder reset-state --state in-use 616dbaa6-f5a5-4f06-9855-fdf222847f3e

Start the instance back up again

Start the instance again:

$ nova start ResizeMe0

Voila! Your old instance is now running with an increased disk size as requested.